Effect of W on activity of Pt–Ru/C catalyst for methanol electrooxidation in acidic medium

Abstract

The effect of W on the activity of Pt–Ru/C catalyst was investigated. The Pt–Ru–W/C and Pt–Ru/C-TR catalysts were prepared by thermal reduction method. Comparison was made to a homemade Pt–Ru/C-CR catalyst prepared by chemical reduction. Their performances were tested by using a glassy carbon thin film electrode through cyclic voltammetric and chronoamperometric curves. The particle size, structure, composition, and surface state of homemade catalyst were determined by means of X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and X-ray photoelectron spectrometry (XPS). The result of XRD analysis shows that the homemade ternary catalyst exhibits face-centered cubic structure and has smaller lattice parameter than Pt-alone and homemade Pt–Ru/C catalysts. The particle size of Pt–Ru–W/C catalyst is relatively large of 6.5 nm. Its electrochemically active specific area is 20 m 2 g −1 less than that of Pt–Ru/C-CR, and much twice as big as that of Pt–Ru/C-TR. But, XPS analysis shows that the addition of W changes the surface state of Pt components in the alloy and can clean Pt surface active sites which are adsorbed by hydrogen. The electrocatalytic activity and tolerance performance to CO ads of Pt–Ru–W/C catalyst for methanol electrooxidation is the best due to the promoting function of W in comparison with homemade Pt–Ru/C ones.